1. Technical Field
This invention relates generally to constant velocity joints and more particularly to those integrated with a wheel hub used for mounting a rotatable wheel of a vehicle.
2. Related Art
It has been proposed in the prior art to integrate a constant velocity joint of a wheel end assembly with the wheel hub of a vehicle, in which case the wheel hub serves as the outer race of the joint. Examples include U.S. Pat. Nos. 4,372,628; 4,421,197; and 4,880,281. In each case, the inner race is installed within the inboard end of the wheel hub opposite the flanged end on which the wheel is mounted, and the torque-transmitting balls disposed in the aligned grooves between the wheel hub and inner race are maintained in a common plane by an intervening ball cage between the inner race and hub. Such assemblies present a rather complex joint configuration that is costly to manufacture and difficult to assemble.
A constant velocity joint constructed according to the present invention simplifies the construction and assembly of such integrated wheel joint assemblies.
A constant velocity joint for a vehicle according to one aspect of the invention comprises a wheel hub which serves as an outer race of the joint which is equipped with wheel mounting structure adjacent a first of its ends that is configured to mount a wheel of a vehicle. The wheel hub has an outer circumferentially extending bearing surface configured to support bearing balls for rotation of the wheel hub about its longitudinal axis relative to support structure of the vehicle. The wheel hub has a longitudinal bore disposed about the axis and including a part spherical surface adjacent an opposite second end of the wheel hub. An inner race is disposed within the bore of the wheel hub and has a part spherical outer surface directly engaging the part spherical surface of the bore and defining a joint center point of the joint about which the wheel hub articulates relative to the inner race. The part spherical surface of the bore extends toward the first end of the wheel hub no further than a plane perpendicular to the longitudinal axis of the bore containing the center point of the joint. The wheel hub and inner race include a plurality of axially extending aligned ball grooves and a torque-transmitting ball in each of the grooves for transmitting torque while permitting relative articulation between the wheel hub and inner race. The grooves of the wheel hub have an associated groove center which is offset axially from the center point on one axial side thereof, and the grooves of the inner race have an associated groove center which is offset axially from the center point on the opposite axial side thereof, such that the balls are forced axially underload toward the first end of the wheel hub. The joint includes the ball retainer device which is disposed within the bore between the balls and first end of the wheel hub which applies a constant bias load to the balls toward the second end maintaining the balls within the grooves in a common ball plane during articulation of the joint.
The invention has the advantage of simplifying the construction and assembly of constant velocity joints integrated with the wheel hub of a vehicle.
The simplified construction includes the direct engagement of the part spherical outer surface of the inner race with the part spherical wall surface of the bore eliminates the intervening ball cage associated with the known prior art constructions.
The provision of the internal ball retainer device in lieu of the normal ball cage reduces the radial size of the joint as compared to known prior art devices and facilitates the assembly of the inner components through the outboard first end of the wheel hub, rather than having to manipulate the various components for installation through the inboard second end as with the known prior art.
According to further aspect of the invention, such a joint is easily assembled by simply installing the inner race and balls within the second end, where the part spherical surfaces engage and the balls are disposed in the ball grooves between the inner race and wheel hub, after which a ball retainer device is installed in the second end to retain the inner race and balls within the wheel hub. This simplified assembly process may be performed by hand or partially or fully automated, thereby simplifying the manufacturing process and reducing the cost of making such integrated wheel joint assemblies.